Method of plating tube sheets



Nov. 25, 1952 H. MORRIS ETAL 2,618,846

METHOD OF PLATING TUBE SHEEITS Filed Aug. 15, 19 47 JNVENTORS j Patented Nov. 25, 1952 METHOD OF PLATING TUBE SHEETS Layne H. Morris, Seelyville, and Ralph W. Parrish, Honesdale, Pa., assignors to The Lu mmus Company, New York, N. Y., a corporation of Delaware Application August 15, 1947, Serial No. 768,780

6 Claims.

This invention relates to the production of plated tube sheets for heat exchangers, or the like.

In the plating of tube sheets, according to one practice, a corrosion-resisting metal alloy is applied in a fused state to one face of a tube sheet blank both of whose faces are flat and parallel and, after the applied metal has hardened, the blank is machined to render its opposite faces fiat and parallel, the tube holes are drilled and other finishing operations, such as marching to provide gasket seats, are performed. As the applied plating metal hardens and cools, it sets up severe contracting stresses which warp the tube sheet and render the plated face of the blank concave and the opposite face convex. Such distortion necessitates the application of more plating metal than is needed to protect the blank, in order to fill the concavity when the blank is warped and thus enable the plating to be machined to a plane surface for accurate drilling of the tube holes and for accurate fitting of the tube sheet within a heat exchanger assembly.

An important object of the present invention is to provide an improved method of producing a plated tube sheet or other plate-like article whereby the plated face of the article will be substantially plane after the plating metal has hardened and cooled so that the necessity for applying excess plating material is avoided and so that a uniform thickness of the plating can be obtained.

Other objects and advantages of the invention will appear hereinafter.

In the drawing, Fig. 1 is a diametrical sectional view of a tube sheet blank prepared to receive the plating metal upon one face thereof;

Fig. 2 is a view similar to Fig. l and showing the plating metal applied in a fused state to the tube sheet blank;

Fig. 3 is a view similar to Fig. 2 showing the sheet.

The invention will be described as employed in the production of a plated tube sheet of cir- 2 cular, disk-like form. However, the utility of the method described is not limited to a tube sheet of that particular form nor is it limited to a tube sheet. Features of the method may be employed advantageously in the production of other plated articles.

In the performance of the method for tube sheet production a tube sheet blank I of the form shown in Fig. 1 is provided. This blank is formed with a cylindrical periphery 2, a flat face 3 and an opposite face 4 which is machined uniformly convex throughout on all diameters so that the thickness of the blank diminishes progressively from the center outward on all radii. In the present instance, the face 4 is shown as provided with an annulargroove 5 in its margin and a diametrical groove 6 connecting opposite sides of the annular groove. These grooves are provided to accommodate a gasket of common form having an annular body portion and a diametrical portion. However, the blank may be formed at either face thereof to accommodate gaskets of any desired form and in any required location. The blank may be formed of any suitable metal such as a mild carbon steel, or an alloy steel, for examples.

Upon the convex face 4 of the blank, the plating metal 1 in a fused state is applied to a desired depth. Such metal may be applied in any suitable manner. For example, it may be applied by moving a weld rod of the metal over the face 4 and fusing the rod by an electric are, or by oxyacetylene or hydrogen flame. Preferably, the application of the metal is commenced at the center of the face 4 and advanced in a spiral to the outer boundary of the area to be covered. In the present instance, the plating metal should be corrosion resistant and the metal chosen may be a suitable alloy such as nickel-copper, coppernickel or a chrome stainless steel alloy, for examples. The invention is of particular utility when the alloy is one comprising approximately nickel and copper because of the high shrinkage of such an alloy.

As the applied plating metal hardens and cools upon the tube sheet blank, it sets up severe contracting stresses which warp the blank into the shape shown in Fig. 3. The plated face 4 is rendered substantially plane and the convexity of the face 4 is displaced to the opposite face 3. The size and proportions of the blank shown in Fig. 1 are chosen for proper correlation with the required depth of applied plating metal and the character of said metal to obtain approximately the degree of warping of the blank reside.

thickness of the blank from the edge to the center thereof along all radii a desired control and distribution of the warping effect obtained. As the plating metal hardens. upon the blank the warping effect is observed and, :if itappears H to continue after the plated face has become flat, the warping is arrested by securing to the blank a backing element 8. As shown in Fig. 4, this backing element may be in the form of a flat disk-shaped plate or block of metal. It is'placed against the face 3 which'has become convex and is welded to the blank, as at 9, atpoints spaced around its edge. The backing block-then resists further material warping of the-tubesheet blank and .preserves the plated face of the blank sub stantially fiat. Suchemploymentof the backing plate is particularly desirable when the face l of the blank becomes warped to a fiat form before the required amount of plating metal has been deposited upon the blank. Application of the required additional metal would then cause additional warping of the blank but for the resistance provided by the backing plate. 7

After the plating metal has fully hardened, the

plated blank and the attached backing plate are heated to relieve them of internal stresses. This heating may be done by placing the-blank and plate in a'furnace. After stress relief thebacking plate is detached frornthe blank by breaking the welds 9.

The blank thus plated is finished by machining the convexity from theface 3 to render theface .flat and parallel to the face 4, furthermachining the'face 3 to provide it with a depressed margin ID for a gasket seat, machining the plating :1

smooth, andgrooving the metal thereof overlying shown at H, and a portion of a channel at 12.

The shell and channel have opposed flangedends bolted together, with the plated tube sheet therebetween and with its plated face at the channel The channel has an annular rib bearin upon thegasket l3 seated within thegroovesfia 'andba, and a-pass, partition ldwithln the-channel'has an edge thereof bearing upcnxthecross portion of said gasket. Anotherl gasket l5...isinterposed between the margin l0 ofthe tube sheet and the opposed'end of the shell H. i Two groups of tubes T joined to the tube sheet communicate respectively with the 'channel-members at opposite side of the .pass partition M. It will b understood, of course, that the tube sheet may be modified to suit different pass partition arrangements and different arrangements of the askets.

The plated face of the tube sheet may also be "upon the shell side of the'sheetinstead of the 4 modifications as are included within the scope of the following claims.

We claim:

1. The method of producing a plated article, comprising providing a plate-like metal blank of the article convex at one face and substantially plane at the opposite face thereof, and in which the highest point of said convexity is at the center of the blank and the depth of said convexity at its highest point comprises only a minor portion of the maximum thickness of the blank, applying: in a fusedstate and in bead form to said blankcver the convex face thereof plating metal having a higher-coefficient of expansion than the metal of the blankand capable of a strong bond therewith, maintaining said metal application substantially symmetrical around the center of the blank as the application progresses, and warping the blank, while free from external restraint of warping,.by contraction of the applied metal as same solidifies and cools to render the said opposite face of the blank convex and render the plated face approximately plane.

v2. The method claimed inclaim .l, whereinthe metal of said blank is carbon steel and thesaid plating metal is a nickel copper alloy.

7 3. The'method'of producing a plated article, comprising providinga plate-like metalblank of the article convex at one face and substantially plane at the opposite face thereof, and in which the highest point of said convexity isat thecenter of the blank and the depth of said convexity at its highest point comprises only a minorportion of the maximum thickness of the blank, applying in a fused state to said blank over the convex face thereof plating metal havin a higher coefficient of expansion than the metal.0f the blank-and capable ofa strong bond therewith, warping the blank, while free from external restraint of warping, by contraction of the applied metal as same solidifies and cools to renderthe said opposite faceof the blank convexand-ren- 'der the plated face approximately plane, imposing'external restraint upon the blank to prevent further'warping, heating the blank while so restrained to relieve same of internal stresses,.and

removing the'convexity from said opposite face of the blank.

4. The method of producing a plated article, comprising providing a metal plate-like blankof the article convex at one face and with the highest point of said convexity at the center of .the blank, and having a groove. in said'face, applying in a fused state to said-blank over the convex face thereof plating metal having a higher coefiicient of expansion than the metal of theblank and capable of a strong bond therewith, and in said application of the plating metal overcharging' the cross section of said groove with said metal, warping the blank, while freefromexternal restraint of Warping, by-contraction of the applied metal as same solidifies and'cools to render the plated face approximately plane, and forming in the applied plating only-a groove directly over and along-said first groove and, narrower than the latter.

5. The'method of producing a plated article, comprising providing a plate-like metal blankof the article circular in outline andsubstantially spherically convex at one face and having the highest point of said convexity at the center of the blank, applying in a fused state to said blank over the convex face thereof plating metal having a higher ccefiicient of expansion than the metal of the blank and capable ofa strong bond therewith, maintaining said metal application substantially symmetrical around the center of the blank by applying the metal progressively entirely around the highest point of the convexity and progressively radially thereof, and warping the blank, while free from external restraint of warping, by contraction of the applied metal as same solidifies and cools, to render the plated face approximately plane.

6. The method of producing a plated article, comprising providing a metal plate-like blank of the article susbstantially circular in outline and substantially spherically convex at one face, applying in a fused state and in bead form to said blank over the convex face thereof plating metal having a higher coefiicient of expansion than the metal of the blank and capable of a strong bond therewith, maintaining said metal application substantially symmetrical around the center of the blank as the application progresses, warping the blank while free from external restraint of warping by contraction of the applied metal as same solidifies and cools to render the plated face approximately plane, placing a metal backing REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,044,897 Boegehold June 23, 1936 2,076,207 Powell Apr. 6, 1937 2,191,470 Hopkins Feb. 27, 1940 2,216,702 Cole Oct. 1, 1940 2,277,654 Merlub-Sobel Mar. 24, 1942 2,299,778 Wissler Oct. 27, 1942 2,390,343 Aske Dec. 4, 1945 

